Roberts has been very public about her health ever since she announced in 2007 that she had been diagnosed with breast cancer. Her many fans follow her on Twitter at @RobinRoberts and often use the hashtag #teamrobin to show their support.

Roberts has spent almost three weeks undergoing aggressive chemotherapy treatment before Thursday's transplant, which, according to a blog post on abcnews.com, will take between 30 and 60 minutes.

Roberts' last tweet on Wednesday read: "JUST completed chemo. Today is day of rest - positive thoughts,words & deeds. How every day should be. Love YOU from bottom of my graeful ?."

As if her health battle wasn't demanding enough on the popular television veteran, Roberts also had to deal with the death of her mother recently. Roberts was scheduled to take an extended medical leave on Aug. 31, but left a day early to return to her Mississippi hometown just after Hurricane Isaac to be with her mother before she died.

Roberts' sister, Sally-Ann Roberts, is the bone marrow donor.

Celebrities Who Have Battled Breast Cancer:

Celebrities who have battled breast cancer

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Christina Applegate - breast cancer

Actress Christina Applegate was 36 when she discovered she had breast cancer in 2008.